All I'm going to tell you is that you have to try to wash the flip flop. You will have to experiment how to do it and once you have completed it, just visit my studio: Work-it-out games and fill in this form on the comments part: How you did it: How long it took: Did you get help or cheat?:
I tried to make it a bit differently but then I thought it might be better to just make it easy instead but not tell anyone how to do it to try and puzzle them and make it a bit more interesting.